Fluid pressure control mechanism



C. 22, 1946. 4 W1 A. EATON 1 2,409,842

FLUID PRESSURE CONTROL MECHANISM Arrow/Vs Oct. 22, 1946.

w. A. AEATQN FLUID PRESSURE CONTROL MECHANISM Filed July 5, 1944 3 Sheets-Sheet 2 l INVENTQJR. WiyredEalbla.

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Oce. 22,` i946.

W. A. EATON FLUID PRESVSURE CONTROL MECHANISM Filed July 5, 1944 3 Sheets-Sheet 5 A Irak/vers Patented Oct. 22, 1946 UNITED `STllTlS PATENT -LOFF ICE .2,409,842 v FLUID PRESSURE CONT-RGL jMECHANISM tWilfred A. `-Eaton, gElyria, Ohio, assgfnor Lto Bendix-Westinghouse Automotive t Brake Company, Elyria, ho, a .corporation QfDEla- Application suits, 1944, serial No. 543,564

13 claims. (ci.

This invention .relates to, control `mechanism and 4more particularly to fluid Vpressure Aoperated mechanism for steering a vehicle.

it has previouslyV been proposed tto provide power .operated mechanism for steering vehicles and `.more particularly fluid pressure operated mechanism wherein :the energization of ia power actuator lis controlled by means of .a lost `motion connection between the .steering Wheel oi v4the Avvehicleand the road `,Wheels of the vehicle, but difiiculty has been experienced on certain vehicles equipped with this type of mechanism due to the fact that road shocks imparted to the road wheels .of the vehicle have tended to take up the .slack in the )lost :motion connection with `a resultant energization of ,the :power ,actuator tending .to cause continuous or vauto-reciprocation of .the ac,- .tuator and of the road Wheels, more commonly known :as jshi-mmy, and it is accordingly an object of the Vpresent ,invention to provide vmeans `for overcoming .this undesirable condition.

,It has :been .found during experiments with mechanisms of this type which ,employ a 4-double acting :iiuid :motor licor .turning the steering wheels in one `direction or "the other, that during rapid reciprocation of the piston of the fluid motor, the control vValves :for the motor ,are .unable .to exhaust uid pressure from the motor Awith sufcient rapidity to prevent the pressure from in.- creasing `at 'the `same time on `both Lsides .fof the piston, aridanother `object lof the :invention fis t0 utilize this simultaneous increase .in pressure on vboth sides `of :the piston for .the purpose of :QP- erating control Valvegrmechanismito reduce the supplyof :fluid Apressure to the ,control .valves of the Arrlotor to a point `Where the udpres- `sx1-.re'suimlytis insufficient to sustain the reeiprwv cation. Y Y

`let.another .object :of the inventionfis to xprovide, n in a .mechanism ,of lthe above type .having a pair fof control valves :for alternately supplying fluid :pressureitoonefend or `:the yother end of the .fluid motor, ,a 'pairof Yconnections each normally operable tosupply huid-pressure from a lreservoir toboth of the .control valves, together with means controlled Joy the spressure inlone end or the motor :,for controlling 'the flowvoof luid preSrSllle through. one of `theseconnections and the pressure `in vthe :other fend Vo f the motor for controle ling the :flow of :fluid pressure through-the `other oftthesel-connections. c n

Still another -object of the yinvention is ,to provide, in a system of the above type having' `ation-- ble :acting fluid .motor :and -a pair .Loffcontrpl valves Afor,;alternatelysupplying fluid pressure-to one end or :the other end of the fiiuid motor, mea-11S responsive to ipressure conditions inthetwo endSuOf the .zmotorgfor controlling thesupply -Qfflluid apres- Surecfrom the msource to the `:control valves fior the; urpose :of fiimitns :the supply tot luid ipresfY `theretoy;,Shellielec;tlyte prerent yor minimize means controlled by pressure `conditiQns in a 1reeiproeating ilnidvmoter ter control-lieg the :W of pressure 'to r:the .control-valves of the moter and .for thus @govemxrsihe speed of .reciproeetionoftheimoter.

,still durther ,object Qi the `,invention is to eproride, Connection with .a `double acting vfluid metor tof the @above type, :means for, supplying suf- .cient fluid zfpressureitepermt :rapid operation of the device fender normal operating conditions, and for `limiting .the supply Lof Vfluid pressureldurine 'autofreiproeationtorfmore rapid operation .to substantial-ly Prevent such reciproeation from ,Continuing i ,These @11d Vother Edesi-roble ohjectsandvieatures of the invention will be @more lreadily `apparent `when taken in connection -Wltli--the ,accompany- .ingdrawingswhereinztwo embodimentsoi the inventionris illustrated. .It :is te .fbe expressly un der stood, however, that the drawings are emfnloyedwf rpiiriloses .of ustratibn only, andere not designed las .a V deniti011 of the limits -Of :the invention, referer-lee :being -hadror this pur-.pose to thetappendedaelaims. l

i @In 4the :dra-wings, wherein :asimilar :reference characters -denote similar lparts throughout ,the Several views;

i rFg. 1 :is :a :diagram-matie view. partially in Secof er :operated steering apparatus utilizin the presentfmventierl; n

Fis.- .12 Vis te :partial seccional view taken alone Fia l, of `the valve :mechanism l for hegsupplyfef fluid pressure to "the `fendjfigxt ,of fthe :mechanism :taken s. and f diagrammatic Mew-.partially inseeten, of ia .ower :steering mechanism embodying anctheriorrnfef the-invention. y

V,RefminstoeFis- .ofthe dreWinsSas-Well as t0 Fig. .ill-fthe steering meehenismiillustrated Vthereiniisfgerlerellygefwt txpeftdiselesedtintthepatent to #Stephen `Yereelrl` en d t Stephen Johnson, ,.Ir., No. ZzllilltL-,defterl Qetober :22, 119,35, thecontrol valve mechanism being substantially the samefas thatishown int-Eig. 2 `el thepatentandthe,leverage mechanism i-f0r `operatingthe .control valve mechanism, although .differing in detail, Qbeing adapteditogefeet operation 4of l:the |control valve meohanismin ythe same Hrmanner as ythe leverage mechanism ,ShOWllln "thegpatent .AS shown .in Eig. f1` of the presentfapplication, the v`power operated mechanism includes la v.steering wheel .4 mounted on the puppen end fof-a `rotatable shaft 5, the shaft Aloeinc)providerl atlits lower end :with 1 a Worm@ adapted @te .engage a :Worm sector .1 havmounted in any suitable manner on a` shaft Scarried by the framework of 4the vehicle, not shown.

The arrangement of the worm and worm sectorv is such that on rota-tion of the steering wheel in' a counterclockwise direction; as viewed bythe one; 's

crater, the sector and lever will be operated in a clockwise direction about the shaft 9 to steer the Y vehicle to the left, and will be'operated in the op- The dirigible wheels of the vehicle, notsl'1 0vvn,.

are connected in the conventional manne-rte a drag link lil having a pivotal connection II with vthe-lower endV of an'operating -lever I2, pivotally mounted for rotation on alsh'aftl I3 carriedon the framework of the vehicle, and a mechanical connection between the lever I2 and the l'ever 8 is eifected byl means of a connecting link I4 pivotally connected to the lever I2- by means 'of a pirr l5 and pivotally connected tov a valve operating lever I6 by means of a pin I1, the lower end of the valve operating leverbeing connected with thelever 8 bymeans of a connecting rod I8y having a universal jointy connection I9 with the leverfIS and a universal joint connection vwith the lever 8. The lever 1:6 Vis supported on afpivot pin `2| 'carried by a lever 22 mounted for free rotating movement onga shaft 23 rigidly mounted on the frame, the 'arrangement-of the lever and shaft being more fully illustrated in'lig. 2. AAs shown in Fig. 2, the upper end of the lever I6 is provided with a hubiportion 24 having an 'l enlarged bore 25" in 'spaced relationship with the vsurface of a portion 26 ofthe shaft 23,'and the llevers 22 and 'I6 are maintained on lthe shaft "23V between a shoulder 21 formed thereon and a washer 28 retained on" the end of the shaft by means of a suitable nut 29; vrllhus the lever I61is so supported asto permit the enlargedbore 25 tonnormally assume a concentric relationship with theshaft portion 26, it thus being apparent that'on movernent'ofv the lever lin' a clockwise direction about the pivot pin I1, the hub portion of thelever will tend toumoveto the right until the leftside of the enlarged bore engages theleft side of the shaft portion 26. n As soon as this engagement oc` curs, further movement ofv the lever-v I6 in fthe same direction fdueto' continued operation of the 'connecting rod '318 byjy the steering mechanism described, Will canse` the lever to pivotabout the line of engagement between the surface ofthe enlarged bore and the surfaceof the shaft portion 28, and the movementof I'the leverwill acvcordingly be imparted to the lever I2 through the connecting rod I4,"`wit h -thelresult that'thedrag link Ill will be moved tothe left to `steer the vehicle mechanically in that directiong'g--Thus the lever I 6i is vpern'iitted Y to' lrock "through" av limited arc in either direction'about the pivot Vpin I 1, and this movement is utilized to operate control mechanism for a power actuator connected with the leve'r I2.` y' The hub '24- of thelever I6,-` as shown inAFig. 2, isprovided with aportion 3U adapted to receive a ring Imember 3l rotatably mounted thereon,- and the ring member is provided with a valve'operat-V ing rod,32 for operating the valve mechanism;

As shown in Fig. 1, a double acting uid motorl33 is provided having a cylinder 34and a piston 35 slidably mounted therein,"a connecting rod 3gpivotallyconnected withthe piston by means of a pivot pin31 being connectedat its leftend with the lever l2 by 'means of a Vpivot pin 38.

A tubular extension 39 serving to enclose the rod 36'is threadedly received Aby the piston and eX- tends to the left through a seal 40' provided in 4the Wall 4I of the cylinder, the right end of the cylinder being closed by a cover plate 42. A con- ;trol valverrrnechanism 43 comprising a pair of identical control valves 44 and 45 is mounted on the upper side of the fluid motor 33 as shown, the

f control valve L44 being adapted to supply fluid l0' pressure tothe right end of the motor through a passage 46, and the valve 45 being adapted to supply fluid pressure to the left end of the motor through ra passage 41. As shown in more detail in Fig. 2, the control Valve is generally of the type disclosed in the above referred to Vorech and Johnson patent. Each of these :valves :isiad'apted to` be selectively operated bymeans 'offa .rocker arm 48 pivotally mounted on the valve mechanism by means of a pivot pin 49, rotationtof the rocker armnin a clockwise direction being adapted vto operatethe valve 44:, 'and rotation' in the other Idirection being adapted to voperate the valve 45,

operation of the rocker arm by movement ofthe lever .I6 being accomplished by means of a; lever 50 formed on the Varm and connected withfthe valve operating rod 32 byvmeans of a universal joint 5I. Each ofthe vvalve mechanisms44. and '45 includes a normally open exhaust valve 52 and normally closed inlet valve 53. `Each ofthe latter valves is resiliently urged againstfa seat 54 by meansfof a spring 55. The exhaustvvalves' are adapted to cooperatefwith seats 56 formed-on pistons 57 slidably received in cylinders 58 formed yin the control valves, the pistons being normally urged upward by means of springs 59. Valve ac- Y tuating stems Eil are slidably mountedin cover members 6l carried on the control valves andare directly connected or integrally formed with the pistons 51. Each of the valves 44 and 451s provided with an inletl and supply'conne'ction 62, the valve 44 being provided with van routlet chamber 63 and the valve 45 being provided withan outlet 4 chamber 64. With.V the exhaust valves inthe position shown, these chambers are con-f nected with atmosphere through" passages 65 formed in the pistons and a common exhaust pas-l sage 66 provided with an exhaustport 6l'. Thus onclockwise operation of the rockerarm to move I'one ofthe plungers 60 downward,.the exhaust valve ofthe valveV 44 is closed andthe inlet valve is opened to admit fluid pressure to"-1the'futlet chamber 63, while on operation ofthe rocker arm in the opposite direction, the plunger 6I) `of'the valve 45 is moveddownward'to` closefthe exhaust valve and open theinlet valve to admit fluidpres-w sure-"to the-outlet chamber` 64. As indicated in' FigfZ and alsoshown in"Fig. 1, the 'outlet chambers 63 and 64 are connected respectivelywith the pass'agesvMA and il-leading to the right and left ends of the cylinder, the valvet44 thus serving to control the pressure of fluid in'the right end of the cylinden'while the valve 45 serves to control the pressure in the otherend of the cylinder. TheV right and left inlet passages 62 of thevalve mechanism are connectedby means of a vconduit 68 which is adapted to receivefluid pressurefrom a supply reservoir l69 through means to be .herein-Y after described. -Y f -4 S `In steering mechanisms of this't'ypath .reser voir is normally directly connected with the-inlet ports of the control valves, but in the presentinstance,v a control valve mechanism "I0 is inter'- posed-betweenthe reservoir and thefconduit` 6'8 leading to the valves 44 and 45, this valve mechanism being provided with an inlet port H y connected with the reservoir 69 through a conduit 12, and an outlet port 13 connected with the conduit 68 by means of a conduit 14. Apair of iluid receiving-passages 15 and 16 are formed in the valve mechanism lilas shown and both connected to the inlet port 1I by means of a passage 11, thece'ntral portions of these passages being connected by means of a bore 18 Which is connected with the outlet port 13 by means of a passage 19, it thus being apparent that both passages 15 and 16 are connected by means of a common conduit 12 with the reservoir 69, and are both connected through passage 18, passage 19 and outlet port 13 with the valve supply conduit 68 through a conduit 14. A valve 8l) slidably mounted in the valvemechanism 1B is adapted on movement to the left to close the right end of the bore 18, a valve 8| similarly mounted .in the left end of the mechanism 1)Y being adapted on movement to the right to close the left end of the bore 18. The mechanism 'lil is provided-at the right end with chambers 82 and 83 separated by means of a flexible diaphragm 84, the central portion of the diaphragm being suitably clamped to the valve member 80 as shown, with a spring 85 interposed between a portion of the mechanism and the diaphragm serving to normally maintain the Valve in the open position shown. In like manner the left end of the mechanism is provided with chambers86 and 81 separated by means of a diaphragm 88` connected with valve 8 l, and a spring 89 serves tomaintain the valve 8| in open position under normal operating conditions. Thus with the parts` in--the position shown, the inlet and outlet ports 'il and 13 are connected through both of the passages 15 and 16, and in the event one of the valves 88 and 8l is closed, the passage not closed by one of the valves will serve to permit the continued flow of fluid pressure from the reservoir tothe control valves ofthe fluid motor.

As heretofore stated, steering mechanism of the above type have a tendency toward auto-reciprocation, the power necessary to maintain this reciprocation being supplied from the iiuid pressure reservoir, and during such reciprocation, it has been found that the valvesf44 and 45 are unable to exhaust `iiuid pressure from the cylinder 34 with sufficient rapidity to alternately reduce thefpressure in one end or the other of the cylinder to that of the surrounding atmosphere, and

as reciprocation continues, there is a tendency for this residual pressure to increase to an appreciable degree, due to the fact -that the valves have insuihcient capaci-ty to handle the large volume of fluid being utilized in sustaining the reciprocation. As indicated hereinabove, this action is utilized to control mechanism `for controlling the supply of uid pressure tothe control valves-44 and 45, and to this end, the passage 46 leading to the right end of the cylinderv is connected tothe chamber 33 of the valve mechanism 'I8 through a conduit 98, whlethe passage 47 leading from the control valve 45 to the left` end of the cylinder is connected with the chamber 81v through a conduit 98a, it being noted iin this connection that the chambers 82 and B5 are at all times Vented to atmosphere through ports` 9i'. Thus when iluid pressure is supplied to the right end ofthe cylinder, this pressure is likewise conducted to the chamber 83 and serves to move the diaphragm 84 to the left tol move the valve 89 to closed position, but in view of the fact that the left end of the cylinder is at atmospheric pressureduring this ltype of op eration, the valve 81 remains in open position,

andfluid pressure is supplied to both of the condtrol Valves 44 and 45 from the reservoir through conduit 12, inlet port 1I, passage 10, passage 16, bore "i8, passage 19, outlet port 13', and conduits 14 and 68, it being apparent that in the event both of the valves 80 and 8| are simultaneously closed, or partially closed, the supply of fluid pressure to the valves 44 and 45 will be substantially reduced, with the result that insuiicient iluid pressure may be supplied to the control valves on the cylinder, to supply the power neces sary to` sustain auto-reciprocation.

Assuming for example that the lever 8 is moved in a counterclockwise direction to steer the vehicle tothe right, the lever I6 will be rotated about the pivot I1 in a counterclockwise direction by virtue of its connection with the lever 8 through the connecting rod I8, and the hub portion 24 will be moved to the left until the rightwall of the enlarged bore contacts the surface of the shaft portion 26, thus serving to move thev valve operating rod 32 to the left to impart counterclockwise rotation to the rocker arm 48 as viewed in Fig. 2. When this occurs, the plunger 60 of the valve 45 will be moved downward to close the intake valve and open the exhaust valve, whereupon fluid pressure will be supplied from the reservoir to the left end of the cylinder through conduit 12 inlet port 1|, passage 11, passages 15 and 16, bore 18, passage 19, port 13, conduits 'i4 and B8, inlet port 62, open inlet valve 53, outlet chamber 64, and passage A41, thus forcing the piston to the right to impart counterclockwise rotation to the lever I2 by virtue of its connection therewith through connecting rod 36, thus moving the drag link I0 to the right to turn the dirigble wheels of the vehicle to steer the vehicle to the right. As the pressure increases in the left end of the cylinder, the pressure will likewise increase in the chamber 81- of the valve mechanism 10, and when this pressure is sufficient to overcome the tension of the spring' 89, the valve 8| Will be moved to the right to close the left end of the bore 18 in order to pre- 45 vent further communication between passage 11 and the bore 18 through the passage 16. The

passage 15will be still effective, however, to permit the flow of iluid pressure to the conduit 14 and to theicontrol valves through the right end 50 of the bore 18, andthe mechanism is so adjusted that during normal operation of the steering mechanism, one of the valves 80 and 8l will always be in open position in order to insure a supply of fluid pressure to the control valves 44 and 45 suflicient to elect eiicient and satisfactory operation of-i the steering mechanism. In the event auto-reciprocation of the piston 35 occurs, however, the valves 44 and 45 will be rapidly operated alternately by movement of the rocker arm48 to rapidly supply iiuid pressure to the cylinder and to exhaust fluid pressure therefrom, and `due to the rapidity of the reciprocation, neither end of the cylinder is completely eX- hausted ofV uid pressure, with the result that the pressure gradually increases in both ends of the cylinder to a value` sufficient to move the diaphragms 84 and 88 against thetensionfof' the springs 85 and 89 to simultaneously close or partially close both of the valves 88 and 8|.` This action occurs almost instantaneously when the auto-reciprocationof the piston 35 is initiated, and as a result of the closing or partial. closing ofthe valves in 'response to the simultaneous in` crease of pressure in both ends of the cylinder,

the supply of fluid pressure-from the reservoir to both of the control valves through the passages 15 and .16 and the bore i8 is either substantially reduced or entirely cut olf until such time as the pressures in the ends of the cylinder and in the chambers 83 and 81 drop sufliciently to permit the valves 80 and 8| to be moved to open position by the operation of ythe springs 85 and 8D. During normal operation, however, operation of the valve44 to supply air to the right end of vthe cylinder causes pressure to be supplied to the right end of the valve mechanism 10 to close the valve 80, but on operation of the rocker arm to operate the valve 45, inresponse to reverse operation of the rocker arm when the steering wheel 4l is turned Vin the opposite direction by the vehicle operator, the speed of operation is suchas to permit the valve 44 to exhaust the right end of the cylinder sufficiently to permit opening of the valve 89 in the valve mechanism 19 before the pressure of fluid in the left end of the cylinder and in the chamberf'l is sufficient toclose thevalve 8|, the result being that during this type of operation, one or the other of the valves 80 or 8| isalways open and iluid pressure is supplied at all times to the inlet ports of both 'of the control valves44 and 45. When the auto-reciprocation occurs, the operation is such that, as hereinabove described, both valves tend to close or partially close at the same time, and the pressure at which such closing of both valves occurs can be `readily adjusted by properly proportioning the areas of the diaphragms and the characteristics of the springs 85 and 89, these being preferably adjusted in such amanner that simultaneous closing of both valves will occur when vthe pressures on both sides of the piston 35 exceed atmospheric pressure at the same time by a predetermined value. Y

. Referring now to the embodiment of the invention shown in Fig. 4, it will 4be seen that the mechanism for controlling the steering of the vehicle is identical to that shown in Fig. 1, the difference being in the means utilized for supplying uid pressure from the reservoir 69 to the inlet ports of the control valves 44 and 45. In view of the explanation given in the preceding paragraph, it will be readily understood that during normal operation of the steering mechanismA by operation of the steering wheel 4, the averagerate at which fluid pressure must be supplied to the control valves to insure satisfactory operation of the uid motor is considerably less than that required to maintain auto-reciprocation, and that through the inclusion of means in the fluid pressure supplyV system which4 is operative to re-duce or Alimit the supply of fluid pressure Vto the control valves during auto-reciprocation, this reciprocation may be minimized or substantially eliminated. Tothis end, fluid pressure is supplied rfrom the reservoir 69 to the conduit 14 leading to the control valves 44 and 454 through a conduit 92 provided with a choke or restricted portion 93 and an auxiliary reservoir 94, the capacity of the auxiliary reservoir being sucient to insure satisfactory operation ofthe steering gear cylinder during a normal steering operation to the left or right of the straight ahead position, but being insuicient to sustain autoreciprocation of the mechanism. In other words, as'soon as auto-reciprocation starts, the pressure in the auxiliary reservoir is materially'reduced due to the additional fluid pressure required to sustain this auto-reciprocation, andthe rate of feed of fluid pressure to the control valves 44 and 45 through conduit 92, choke `33, reservoir 94 and 8 conduit14 is governed by the choke. Thesize ofthis choke isk so vchosen as t limit the supply of fluid pressure to the control valves to a value slightly less than that required to sustain autoreciprocation In this connection, it is pointed out that chokes have previously been utilized for this purpose, but that in most cases thesechokes have been interposed in the passages 46'and 41 adjacent the cylinder. The use of chokes in this manner has been of material advantage in minimizing or eliminating auto-reciprocation, but at the same time 'has so limited the supply of uid pressure to the cylinder as to prevent the latter fromv supplying the necessary amount of power to insure sulciently rapid operation of the steering mechanism when the steering wheel is turned by the operator. Due to the location of the choke as shown between the main reservoir and the auxiliary-reservoir, it will be readily apparent that the relatively small `auxiliary reservoir supplies sucient fluid pressure to permit the cylinder to supply the necessary amount of power t0 operate the steering mechanism when the steering wheel is turned Iby the operator of the vehicle, but that during auto-reciprocation, when a continuous supply of fluid pressure is required by the control valves and cylinder and the operation is much more rapid, the pressure in the reservoir 94 is rapidly depleted to a point Where the flow of iluid pressure to the control valves is governedentirely by the choke 93, and it is thus possible to choose a choke size and auxiliary reservoir size which will prevent auto-reciprocation and which at the same time will supply sufficient -uid pressure to maintain a normal working pressure in the auxiliary reservoir during operationof the mechanism at normal speeds. s 'There has thus `been provided in the present invention, as illustrated in the embodiments shown more particularly in Figs. 1 and 4, simple and eincient means for normally supplying suflicient uid pressure from the main reservoir to the steering mechanism to insure satisfactory and unrestricted operation, together with means for automatically limiting the supply of fluid pressure to a value which is insuiiicient to sustain auto-reciprocation of the mechanism when such reciprocation occurs or tends to occur.

While two embodiments of the invention have been illustratedand described with considerable detail, it will be readily understood by those v skilled in theV art that various changes, substitutions, and rearrangements of the component parts may be resorted to without departing from the spirit of theA invention. It is also to be understood that the principles set forth may be embodied in connection withV any suitable power medium for effecting and controllingthe operation of a fluid motor or power actuator. Reference will, therefore, be yhad to the appended claims for a definition of the limits of the invention.

What is claimed is:

i1. Mechanism for controlling the supply of fluid pressure from a source ,to a double acting flui-d motor of the type having a pair of control valves and a control elementvfor operating said valves to alternately supply iluid pressure to one end or the other end of said motor, said mechanism including a pair of connections eachv adapted to connect the source with both valves, and means responsive to the pressure in one end of the motor for closing one of said connectionsA and responsive to the pressure in the other endl of the motor for closing the other'of said con--` nections when said pressures reach predetermined values. l l

2.v Mecha-nism, for controlling the supply of fluid pressure from a source to a double acting fluid motor of `the type having a pairV of control valves and a control elementfor operating said valves to alternately supply fluid pressure to one end or the other end of said motor, said mechanism including a pair of connections each adapted to connect the source with both valves, and means controlled by the pressure in the motor for .controlling theflow of fluid pressure through said connections including a valve forclosing one of the connections when the pressure in one end of `the motor reaches a .predetermined value and a valve for closing the other connection when the pressure in the other end of `Athe motor reaches a predetermined Value.

3. Mechanism for controlling the supply of uid pressure from a source to a double acting fluid motor of the type having a pair of control valves and a control element for operatingV said valves to alternately supply fluid pressure to one end or the other end of said motor, said mechanism including a pair of connections each adapted to connect the source with both valves,`and valve means controlled by the pressure in Vone end of the motor for controlling the flow 'of fluid pressure through one of said lconnections and controlled by the pressure in the other end of the motor for controlling the flow of fluid pressure through the other of said connections.

4. Mechanism for controlling the supply of fluid pressure from a source to a double acting uid motor of the type having a pair of control valves and a control element for operating said valves to alternately supply fluid pressure to one end or the other end of said motor, said mechanism including a pair of connections each adapted to connect the source with both control valves, a separate valve for controlling the flow of fluid pressure through one of said connections, means responsive to the pressure in one end of the motor for closing said separate valve when the rpressure in said one end of the motor reaches a predetermined value, a valve for controlling the llow of fluid pressure through the other of said connections, and means responsive to the pressure in the other end of the motor for closing the last named valve when the pressure in said other end of the motor reaches a predetermined value.

5. Mechanism for controlling the supply of fluid pressure from a source to a double acting fluid motor of the type having va pair of control valves and a control element for operating said valves to alternately supply fluid pressure to one end or the other end of said motor, said mechanism including a pair of connections each adapted to connect the source with both control valves, a separate valve for controlling the flow of fluid pressure through each of said connections, means for normally maintaining said separate valves in open position, means responsive to the pressure in one end of the motor for moving one of said separate valves to closed position, and means resp-onsive to the pressure in the other end of the motor for moving the other of said separate valves to closed position.

6. Mechanism for controlling the supply of fluid pressure from a source to a double acting fluid motor of the type having a pair of control valves and a control element for operating said valves to alternately supply fluid pressure to one end or the other end of said motor, said mechanism including a pair of connections each adapted to connect the source with both control valves, means responsive'to thepressure in onefend of the motor for closing one of said connections when the pressure in said one end exceeds va predetermined value, andmeans `responsive to the pressure in the `other end of the motorfor closing the other of said connections when the pressure in said other end exceeds a predetermined value.

7. rllhe combination with a source of fluid pressure, a double acting fluid motor, ,valvel mechanism operableto alternately `supply fluidpressure to one end or to the other end of said motor, `and meansforconnecting said sourceand valve mechanism, of means associated with said connection means` controlled by the; pressure in said motor for reducing the flow of fluid pressurebetween the source and valve mechanism when the pressures in both ends of said motor exceed a predetermined value at the same time including a valve controlled by the pressure in one end of the motor and another valve controlled by the pressure in the other end of the motor.

8. The combination with a source of 'll-uid pressure, a double acting-fluid motor, valve mechanism operable to alternately supply fluid pressure' to one end or to the other end of said moto-r, and means for connecting .said source and valve mechanisrn, of vvalve means associated with said con-- necting means for controlling the flow of fluid pressure therethrough between said source and motor, said valve means including a pair of passages having a `common connection with the valve mechanism and a common connection with the source, a separatevalvefor controlling the flow of fluid pressure in" each'of saidp'a'ssages, means controlled by variations in the pressure of fluid in one end of the motor for opening and closing one of said separate Valves, and means controlled by variations in the pressure of liuid in the other end of the motor for opening and closing the other of said separate valves.

9. The combination with a source of power, a reversible power actuator, control mechanism operable to alternately energize the actuator for operation in one direction or the other, and means for supplying power from said source to said control mechanism, of control means associated with said supplying means for controlling the degree of power supplied to said control mechanism, said control means including means forming a pair of power supply paths having a common connection with the source and a common connection with the control mechanism, a power controlling element for controlling the degree of power supplied to the control mechanism along each of said paths, means responsive to the power supplied to the actuator to operate it in one direction for controlling the operation of one of said elements, and means responsive to the power supplied to the actuator to operate it in the other direction for controlling the operation of the other of said elements.

10. Mechanism for controlling the supply of` power to a power operated device of the type having a reversible power actuator and control means operable to alternately energize the actu-- ator Afor operation in one direction or the other, said mechanism including means providing a pair of parallel power paths for supplying power to the control means, means responsive to the power supplied to the actuator to operate it in one direction for controlling the degree of power supplied to the control means along one: of said paths,A and means responsive to the power supplied to the actuator to operate it in the opposite direction for controlling thedegree of power suD- y plied to the control means along said paths.

1l. Control valve mechanism for controlling the supply of fluid pressure to a double acting fluid pressure motor of the type having a pair of control valves and an element for operating said valves to alternately supply fluid pressure to one end or to the other end of said motor, said valve mechanism including a casing having an inlet port adapted to be connected toa source of fluid pressure', anoutlet port adapted to be connected to each of said control valves, a pair of fluid pressure passages both connected with the inlet port and with the outlet port, separate valves for centrolling the flow of fluid pressure through each of said passages, means for normally maintaining said valves in open position, a chamber adapted to be connected to one end of the motor, a chamber adapted to be connected to the other end of the motor, a member subjected to the pressure of fluid in the first named chamber for operating one of said separate valves, and a member subjected to the pressure offluid in the other of said chambers for operating the other of vsaid separate valves.

12. The combination with a double acting fluid motor of the type having control valve mechanism adapted to supply uid pressure alternately to opposite ends of -the motor to effect reciprocation thereof at different rates dependent on the speed of operation of the valve mechanism and a source of fluid pressure for said valve mechanism, of means for limiting the speed of reciprocation Iof said motor to a predetermined value the vother of regardless of the speed of Voperation of said valve mechanism including a connection between the source vand valve mechanism,` and'm'e'ans including a. pair of valves controlled respectively by the pressures of the fluid -in opposite ends of the motor for controlling the flow of fluid pressure throughsaid connection.

' 13. Control valve mechanism for controlling the supply of fluid pressure to a double acting fluid -motor of the type having a pair of control valves and means for operating one ofsaid valves to supply fluid pressure to one end ofthe motor and for operating the other of said valves to supply fluid pressure `to the other end of the motor, said control valve mechanism including a casing having an inlet port adapted to be connected to a source of fluid pressure, an' outlet port lhaving a connection With each of said control valves, a pair of separate fluid passages each connected with the inlet and outlet ports, separate valves for controlling thel flow of fluid pressure through each of said passages, a pressure responsive member subjected at `all times to the pressure of fluid in one end of the motor for closing one of said separate valves, a pressure responsive member subjected at all times to the pressure of fluid in the other end of the motor for closing the `other of said separate valves, and separatesprings for normally maintaining each of said separate Valves in open position until the pressure of the fluid to which eachV of -the corresponding pressure responsive members is subjected reaches a predetermined value.

WILFRED A. EATON. 

